The broad objectives of our research are as follows: (a) To study the possibility of simulating in the laboratory the type of chemical processes that are involved in the key step in the biogenesis of naturally occurring cyclic terpenoids, including the steroids. This key step is the cyclization process which proceeds, in vivo, with extraordinary structural-and stereo-specificity; (b) to examine systems which are designed to shed light on the intimate mechanism of the key cyclization step in the aforementioned biosyntheses; (c) to attempt to apply biogenetic-like cyclizations to the total synthesis of polycycloisoprenoid systems, particularly the steroids. This study envisages a basically new synthetic approach to natural products of importance in medicine and life processes; (d) to continue certain classical-type synthetic projects directed toward the production of natural products that have not yet been totally synthesized, e.g., some of the important terpenoids; (e) to exploit any especially novel behavior or reactions encountered in the process of the aforementioned studies. Immediate objectives include: novel, efficient methods of synthesizing cortisone; 19-nor steroid oral contraceptives; steroid analogs particularly those with 11 alpha- substituents; the biologically potent metabolite 1 alpha,25-dihydroxy vitamin D3; protosterol types related to the antifungal agent fusidic acid; and the tumor-inhibitor taxodione.